Abstract
Paleoclimate research on Central North American droughts can help reconstruct regional climate effects that leave America’s agricultural areas vulnerable to future droughts. The past climate of the White River Badlands (WRB), located in the northwestern Great Plains, is poorly understood, due to the lack of traditional paleoclimate proxies in the area. However, with geochemical analyses of fossils preserved within mesa material there, we constrained the age of sediment deposition in this region and characterized climatic forces associated with last glacial drought and subsequent (dust) deposition. Geochemical proxies from gastropod fossil shells show that drought-driven dust deposition occurred at the Last Glacial Maximum (LGM), providing a link between cold, continental glacial conditions and aeolian activity. Galba obrussa and Gyralus parvus shells were collected from the lower loess section at Red Dog Table for radiocarbon dating and isotopic analyses. Fossil ages ranged from 24 – 22 ka, aligning with the start of the LGM. We hypothesized that if greater rates of loess accumulation coincide with negative deviations in shell δ18O, decreases in regional precipitation likely coupled with a strong polar jet stream to drive last glacial dust storms. Negative excursions in δ18Oshell from 24 – 22 ka reveal that precipitation decreases coincide with greater loess accumulation rates at the section (2.5 mm/yr). Gastropod δ18O fluxes also correlate with the Greenland Ice Core (GIC) δ18O record, though exhibit pronounced magnitudes associated with heterogeneous local extremes. Our paleoclimate reconstruction temporally constrains last glacial drought in the WRB and distinguishes late Pleistocene droughts from later Holocene megadroughts.
Faculty Sponsors
Dr. Paul Baldauf
Project Type
Event
Location
Alvin Sherman Library
Start Date
4-2-2025 12:45 PM
End Date
4-3-2025 12:00 AM
Last Glacial Maximum Paleoenvironmental Proxies for the White River Badlands, SD
Alvin Sherman Library
Paleoclimate research on Central North American droughts can help reconstruct regional climate effects that leave America’s agricultural areas vulnerable to future droughts. The past climate of the White River Badlands (WRB), located in the northwestern Great Plains, is poorly understood, due to the lack of traditional paleoclimate proxies in the area. However, with geochemical analyses of fossils preserved within mesa material there, we constrained the age of sediment deposition in this region and characterized climatic forces associated with last glacial drought and subsequent (dust) deposition. Geochemical proxies from gastropod fossil shells show that drought-driven dust deposition occurred at the Last Glacial Maximum (LGM), providing a link between cold, continental glacial conditions and aeolian activity. Galba obrussa and Gyralus parvus shells were collected from the lower loess section at Red Dog Table for radiocarbon dating and isotopic analyses. Fossil ages ranged from 24 – 22 ka, aligning with the start of the LGM. We hypothesized that if greater rates of loess accumulation coincide with negative deviations in shell δ18O, decreases in regional precipitation likely coupled with a strong polar jet stream to drive last glacial dust storms. Negative excursions in δ18Oshell from 24 – 22 ka reveal that precipitation decreases coincide with greater loess accumulation rates at the section (2.5 mm/yr). Gastropod δ18O fluxes also correlate with the Greenland Ice Core (GIC) δ18O record, though exhibit pronounced magnitudes associated with heterogeneous local extremes. Our paleoclimate reconstruction temporally constrains last glacial drought in the WRB and distinguishes late Pleistocene droughts from later Holocene megadroughts.
